JPS627059A - Photosensitive body - Google Patents

Abstract

PURPOSE:To enhance resistances to mechanical damage and printing, to eliminate image flow, to stabilize image quality, to reduce photofatigue due to repeated uses, and to obtain stable characteristics by successively laminating an electrostatic charge transfer layer, a charge generating layer, an interlayer, and a surface modifying layer. CONSTITUTION:A charge blocking layer 44 heavily doped with an element group IIIa or Va of the periodic table and containing one of C and N, and O is formed on a conductive substrate drum 41, further, the charge transfer layer 42 lightly doped with an element of group IIIa to make the layer 42 intrinsic, and containing one of C, N, and O, the charge generating layer 43, the interlayer 46 made of amorphous silicon hydride containing C and O, and the surface modifying layer 45 made of amorphous silicon hydride doped with an element of group Va and containing C and N are laminated on the layer 44 to fabricate the photosensitive body 39, thus permitting the adhesion acceptance potential, and film strength of each of the layers 45, 43 to be enhanced, resistances to mechanical damage and printing to be elevated, stable image quality free from image flow to be obtained, photofatigue due to repeated uses to be reduced, and characteristics to be stabilized.

Description

[Detailed description of the invention]

B. Industrial Application Field The present invention relates to a photoreceptor, for example, an electrophotographic photoreceptor. Conventional technology Conventionally, as an electrophotographic photoreceptor, Se or Se has AS%
Photoconductors doped with Te5Sb or the like, photoconductors in which ZnO or CdS is dispersed in a resin binder, and the like are known. However, these photoreceptors have problems in terms of environmental pollution, thermal stability, and mechanical strength. On the other hand, electrophotographic photoreceptors using amorphous silicon (a-3i) as a matrix have been proposed in recent years. a-3i has a so-called dangling bond in which the bond of 5i-3i is broken, and many localized levels exist within the energy gap due to this defect. For this reason, hopping conduction of thermally excited carriers occurs, resulting in a small dark resistance, and photoexcited carriers are trapped in localized levels, resulting in poor photoconductivity. Therefore, we replaced the above defects with hydrogen atoms (
The dangling bonds are filled by bonding H to St by compensating with H). Such amorphous hydrogenated silicon (hereinafter referred to as a-3
It is called i:H. ) has a resistivity in the dark of 108~1O
9Ω- mark, which is about 1 compared to amorphous Se.
It's even lower than 1/10,000. Therefore, a photoreceptor made of a single layer of a-3tzH has problems in that the dark decay rate of the surface potential is high and the initial charging potential is low. However, on the other hand, when irradiated with light in the visible and infrared regions, the resistivity is greatly reduced, so it has extremely excellent properties as a photosensitive layer of a photoreceptor. Figure 5 shows a-3 using the above ・a-3t:H as the base material.
An electrophotographic copying machine incorporating an i-type photoreceptor 9 is shown. According to this copying machine, a glass document mounting table 3 on which a document 2 is placed and a platen cover 4 that covers the document 2 are disposed in the upper part of a cabinet 1. Below the document table 3, an optical scanning table consisting of a first mirror unit 7 equipped with a light source 5 and a first reflection mirror 6 is provided so as to be movable in a straight line in the left and right direction of the drawing. A second mirror unit 20 for making the optical path length constant moves according to the speed of the first mirror unit, and the reflected light from the document table 3 passes through the lens 21 and the reflection mirror 8 and is reflected as an image carrier. The light is incident on the photosensitive drum 9 in the form of a slit. A corona charger 10 is installed around the drum 9.
, a developing device 11, a transfer section 12, a separation section 13, and a cleaning section 14 are arranged, and the copy paper 18 fed from the paper feed box 15 via each paper feed roller 16, 17 is transferred to the drum 9.
After the toner image is transferred, it is further fixed in the fixing section 19, and then the paper is discharged to the tray 35. In the fixing section 19, a fixing operation is performed by passing the developed copy paper between a heating roller 23 having a built-in heater 22 and a pressure roller 24. However, photoreceptors with a-3i:H surfaces are susceptible to surface chemical stability, such as the effects of long-term exposure to the atmosphere or moisture, and the effects of chemical species generated by corona discharge. , has not been sufficiently investigated so far. For example, items that have been left for more than a month will be affected by moisture.
It is known that the receptor potential is significantly reduced. On the other hand, amorphous hydrogenated silicon carbide (hereinafter a-3iC:H
It is called. ), its manufacturing method and existence are @Ph11.
Mag, Vo1.35'' (197B), etc., and its characteristics include high heat resistance and surface hardness, and a high dark resistivity (10 ~
10 Ω-C11), and that the optical energy gap changes over a range of 1.6 to 2.8 eV depending on the amount of carbon. However, there is a drawback that the long wavelength sensitivity becomes poor due to the widening of the band gap due to the inclusion of carbon. An electrophotographic photoreceptor combining such a-5iC:H and a-3i:H has been proposed, for example, in Japanese Patent Laid-Open No. 127083/1983. According to this, a-3tsH
The layer is a charge generation (photoconductive) layer, and below this charge generation layer is a
-3iC:H layer is provided, the upper layer a-3t:H provides photosensitivity in a wide wavelength range, and the lower layer a-3iC:H forming a heterojunction with the a-3i:H layer has a charged potential. We are working to improve this. However, the dark decay of the a-8i:l (layer) cannot be sufficiently prevented, the charging potential is still insufficient, and it is not practical;
;) The presence of one layer results in poor chemical stability, mechanical strength, heat resistance, etc. On the other hand, JP-A-57-17952 discloses a-3i:
A first a-3iCsH layer is formed as a surface modification layer on the charge generation layer made of H, and a second a-3iCsH layer is formed on the back surface (support electrode side).
A-3iCsH layer is formed. In addition, as related to this known technology,
As seen in Japanese Patent No. 23543, a gradient layer (a-3i1-xCx:H) is provided between the charge generation layer and the first and second a-3iC:H layers, and in this gradient layer, a-St: Set X=0 on the H side, a-3iC: H1'i
A photoreceptor in which X=0.5 on the t side is known. However, when the present inventor conducted a study on the above-mentioned known photoreceptor, it was found that the effect of providing the surface modification layer is not so pronounced, especially in continuous repeated use. That is, during continuous running of 200,000 to 300,000 times, the a-3iC layer on the surface is mechanically damaged after about 70,000 to 80,000 times, and this causes white streaks and white spots as image defects, resulting in poor rigidity. Not enough. Furthermore, light resistance fatigue occurs during repeated use, image blurring occurs, and the electrical and optical characteristics are not always stable, and the effects of the use environment (temperature, humidity) cannot be ignored. Furthermore, it is necessary to further improve the adhesion between the surface modified layer and the charge generation layer. C. Object of the Invention The object of the present invention is to provide excellent adhesion between the surface-modified layer and the charge generation layer, excellent charging ability and film strength, resistance to mechanical damage, and excellent printing durability. To provide a photoreceptor that can provide stable image quality without image blurring, has little optical fatigue during repeated use, has low residual potential, and has stable characteristics regardless of the usage environment (temperature, humidity). be. 2. Structure of the invention and its effects, that is, the present invention comprises a charge transport layer made of amorphous hydrogenated and/or fluorinated silicon containing carbon atoms and/or nitrogen atoms and oxygen atoms; or a charge generation layer made of fluorinated silicon and an amorphous hydrogenated layer containing carbon atoms and oxygen atoms;
Or a photoreceptor in which an intermediate layer made of fluorinated silicon and a surface modified layer made of amorphous hydrogenated and/or fluorinated silicon containing more carbon atoms and oxygen atoms than the intermediate layer are sequentially laminated. This is related. According to the present invention, since the surface modified layer contains carbon and oxygen atoms, it is resistant to mechanical damage, and there is no deterioration in image quality due to white streaks, etc., and it has excellent printing durability. In addition, the presence of oxygen improves charging ability, increases film strength, and stabilizes image quality. Furthermore, in the present invention, an intermediate layer having a lower carbon and oxygen atom content than the surface modified layer is provided between the surface modified layer and the charge generation layer. Improves adhesion and charging ability. Furthermore, since the surface modification layer and intermediate layer are provided on the charge generation layer, in addition to the above, it has excellent resistance to light fatigue during repeated use, no image fading, low residual potential, and electrical resistance. It has been confirmed that the optical properties are always stable and unaffected by the usage environment. E. Examples Hereinafter, the present invention will be explained in detail with reference to examples. FIG. 1 shows an a-3i electrophotographic photoreceptor 3 according to this embodiment.
9. This photoreceptor 39 is mounted on a drum-shaped conductive support substrate 41 such as A1.
a-3i heavily doped with group elements (e.g. boron or phosphorus) and containing at least one of C and N and O:
A charge blocking layer 44 made of H is provided as necessary, and a-3t containing C and/or N and 0 is further provided with a charge blocking layer 44 made of H, which is light-doped with a group IV a element of the periodic table (for example, boron) to make it intrinsic. :H charge transport layer 42 and a-3
i:) (with no impurity doping or made intrinsic) 43; an intermediate layer 46 made of amorphous hydrogenated silicon containing carbon and oxygen atoms; It has a structure in which surface-modified silicon 1i45 made of amorphous hydrogenated silicon doped with elements to make it P-type, N-type, or intrinsic (or not doped with impurities) and containing C and 0 is stacked.Charge The generation layer 43 has a ratio of resistivity ρ in the dark and resistivity ρL during light irradiation, which is sufficiently large as an electrophotographic photoreceptor and has photosensitivity (particularly to light in the visible and infrared regions).
is good. The above layer 45 is essential for modifying the surface of the photoreceptor and making the a-3i photoreceptor practically superior. That is, it enables the basic operations of an electrophotographic photoreceptor, such as charge retention on the surface and attenuation of the surface potential due to light irradiation. Therefore, the repetitive characteristics of charging and optical attenuation become very stable, and good potential characteristics can be reproduced even if left for a long period of time (for example, one month or more). On the other hand, in the case of a photoreceptor having a-3i:H as its surface, it is easily affected by humidity, air, ozone atmosphere, etc., and the potential characteristics change significantly over time. In addition, since the layer 45 has a high surface hardness, it has abrasion resistance during processes such as development, transfer, and cleaning, and also has good heat resistance, so a process that applies heat such as adhesive transfer can be applied. . In order to comprehensively achieve the excellent effects described above, it is important to select the composition of the layer 45. That is, the carbon atom content is S i + C+ O=100
When atomic% (hereinafter, atomic% is simply expressed as %), 1%≦(C)590%, further 10%
It is desirable that ≦[03570%. This C content makes the specific resistance a desired value, and the optical energy gap becomes approximately 2.5 eV or more, and the irradiated light is a-5i:H due to the so-called optically transparent window effect for visible and infrared light. It becomes easier to reach the layer (charge generation layer) 43. However, if the C content is 1% or less, disadvantages such as mechanical damage occur, and the specific resistance tends to fall below a desired value, and part of the light is absorbed by the surface layer 45, reducing the photosensitivity of the photoreceptor. In addition, if the C content exceeds 90%, the amount of carbon in the layer increases, the semiconductor properties are likely to be lost, and the deposition rate when forming a-3iC:HM* by the glow discharge method increases. Therefore, the C content is preferably 90% or less.The oxygen content of the layer 45 is also important;
550% (more preferably 5%≦(0)630%). Further, it is preferable to continuously increase the carbon and/or oxygen content in the surface modified layer from the intermediate layer 46 side to the surface side. In order to improve the charging ability, the surface modified layer 45 may have a high resistance. For this purpose, the surface modified layer may be made intrinsic. In order to facilitate the injection of electrons or holes from the intermediate layer into the surface-modified layer and to minimize the residual potential when positively or negatively charged, the surface-modified layer must be of P or N type. may be,
The amount of impurity doped in each case (at the time of glow discharge decomposition described later) may be as follows. Intrinsic: B2H6/SiH42-50 capacity ppm P type:
BzHa/SiH+ 1-1000 (preferably 5
0 to 500) Capacity ppm N type: PH3/SiH+ 1 to 1000 (preferably 50 to 500) Volume ft ppm Also, the film thickness of layer 45 should be within the range of 400 people ≦ t ≦ 5000 people (especially 400 people ≦ It is also important to select t≦2000 people.In other words, if the film thickness exceeds 5000 people, the residual potential vR will become too high and the photosensitivity will decrease, resulting in poor sensitivity as a-3i type photosensitive. It is easy to lose good characteristics. In addition, if the film thickness is less than 400 mm, the tunnel effect prevents charges from being charged on the surface, resulting in increased dark decay and decreased photosensitivity. Intermediate layer 46 may be made intrinsic for the same reason as mentioned above.Also, in order to lower the residual potential, the intermediate layer may be made of P or N type to enable charge injection from the charge generation layer. Good. The doping amount for controlling the conductivity type may be the same as that of the surface modification layer. The thickness of this intermediate layer should be 50 to 5,000 layers, but if it exceeds 5,000 layers, the same phenomenon as described above will occur. If the number of people is less than 50, the effectiveness of the middle class will be poor.The middle class 46 is 0%<[03590% (furthermore, 10%≦[03570
%), 0% < (0) 550% (even less than 0%)

[0]
It is preferable to set it to ≦30%. ) Alternatively, the intermediate layer 46 may be formed of a plurality of layers, and at least one of the carbon content and oxygen content in the intermediate layer may be increased in stages from the charge generation layer 43 to the surface modified layer 45. Good. Furthermore, the carbon and/or oxygen content can also be gradually increased continuously. Regarding the charge generation layer 43, in order to improve the charging ability, the charge generation layer may be made to have a high resistance. For this purpose, the charge generation layer may be made intrinsic. For this purpose, it is preferable to set B 2 Hs / SiH4 = 1 to 20 ppra. In addition, it may be made into P or N type as necessary to improve sensitivity and reduce residual potential.
For P-type, B2H6/SiH4-20 to 100 ppm -, for N-type, P Ha / Si H
4=1 to 100 ppm by volume. Further, the charge generation layer has a thickness of 1 to 10 μm, preferably 5 to 7 μm.
It is better to set it to m. If the thickness of the charge generation layer 43 is less than 1 μm, the photosensitivity will not be sufficient, and if it exceeds 10 IJm, the residual potential will increase, which is insufficient for practical use. Regarding the charge transport layer 42, in order to optimize charging ability and sensitivity, the charge transport layer may be made intrinsic, P or N type, depending on the carbon (or nitrogen) content and the charging polarity used. Further, the thickness of the charge transport layer is preferably 10 to 30 μm. Specifically, the charge transport layer 42 may be as follows. 5iCO: Intrinsic B2H6/SiH42~20 Capacity pp+mP type BzHs/SiH+ 20~100
0〃N type conversion P H3/S i H41~1000
-5iNO: Intrinsic BzHs/SiH+ 1 to 20
00 PP type BzHs/SiH+ 2000~
3000〃N-type P H3/S i H41~10
00 Also, the composition of the charge transport layer is 1% [035
30%, preferably lO%≦(C) 530%,
1% <(N)530%, preferably 10%≦(N)53
0% is good. Also, 0.05%≦

[0]≦5%, preferably 0.1%≦

[0]≦3% is preferable. When providing the charge blocking layer 44, 0% (C)
530%, preferably 10%≦(C)530%, and 0
% [N] 530%, preferably 10% [N3
It is better to set it to 630%. Also, 0.05%≦

[0]≦
5%, preferably 0.1%≦(0)≦3%. The conductivity type of the blocking layer may be P type (or even P+ type) or intrinsic type (or N type (or even N)) depending on the sensitivity, charging ability, and charging polarity used. The doping amount of the blocking layer is controlled as follows depending on its composition. SiC: Intrinsic B 2 Ha/S i H42-20
Capacity ppmP type (P') B z H6/S
i H420~5000〃N type CN') PH3/S i
H41~1000 SiN: Intrinsic B2H6/SiH
41~2000〃P type (“λ B2H6/SiH420
00~5000〃N type (Lock P Ha / Si H
41 to 2000〃Also, the thickness of the blocking layer is 500
A thickness of ~2 μm is preferable, but if it is less than 500 μm, the blocking effect will be weak, and if it exceeds 2 μm, the charge transport ability will tend to deteriorate. Note that each of the above layers needs to contain hydrogen. In particular, the hydrogen content in the charge generation layer 43 is essential to compensate for dangling bonds and improve photoconductivity and charge retention, and is preferably 10 to 30%. This content range also applies to the surface modification layer 45, blocking layer 44, and charge transport layer 42. In addition, as impurities for controlling the conductivity type of the blocking layer 44, in addition to poron, Al and Ga% can be used to make the blocking layer 44 P-type.
A periodic table ma group element such as I n % T It can be used. In addition to phosphorus, A S SS is needed for N-type conversion.
Group Va elements of the periodic table, such as B, can be used. Next, a method for manufacturing the above-mentioned photoreceptor (for example, drum-shaped) and an apparatus therefor (glow discharge apparatus) will be explained with reference to FIG. A drum-shaped substrate 41 is set rotatably vertically in a vacuum chamber 52 of this device 51, and a heater 55 is used to rotate the substrate 41.
can be heated to a predetermined temperature from the inside. A cylindrical high frequency electrode 57 with a gas outlet 53 is disposed around and facing the substrate 41, and a glow discharge is generated between the electrode 57 and the substrate 41 by a high frequency power source 56. In addition, 62 in the figure is a supply source of SiH4 or a gaseous silicon compound, 63 is a supply source of hydrocarbon gas such as CH4, and 64 is a supply source of N2.
65 is a supply source of oxygen compound gas such as 02, 66 is a carrier gas supply source such as Ar,
67 is an impurity gas (e.g. B 2 Hs) supply source, 68
is each flow needle. In this glow discharge device, first, the surface of a support, for example, an A1 substrate 41, is cleaned and then placed in a vacuum chamber 52, and the gas pressure in the vacuum chamber 52 is set to 10
= Torr and exhaust the air, and the substrate 4
1 at a predetermined temperature, particularly 100 to 350°C (preferably 15°C
Heat and maintain at a temperature of 0 to 300°C. Next, using a high-purity inert gas as a carrier gas, SiH4 or a gaseous silicon compound, CH4, N2.02, etc. are appropriately introduced into the vacuum chamber 52, and the high-frequency power source 56 is used under a reaction pressure of, for example, 0.01 to 10 Torr. High frequency voltage (e.g. 13.56
MHz) is applied. As a result, each of the above-mentioned reaction gases is decomposed by glow discharge between the electrode 57 and the substrate 41, and the P-type a
-3i CO: H, a-3ic. :H,a-3i :H,a-3iCO:H,a-3iC
O:H is deposited as the above-described layer 44, 42, 43, 46, 45 on the substrate in succession (by tapping, eg corresponding to the example of FIG. 1). In the above manufacturing method, the support temperature is set at 100 to 350°C in the step of forming the a-5t layer on the support, so the film quality (especially electrical properties) of the photoreceptor can be improved. . In addition, when forming the above a-3i photoreceptor photosensitive layer,
In order to compensate for dangling bonds, fluorine is introduced in the form of SiF4, etc. in place of the above-mentioned H or in combination with H, and a-Si:F, a-3t:H:F, a-
3iN:F, a-3iN:H:FSa-3i'C:F,
It can also be a-3iC:H:F. In this case, the amount of fluorine is preferably 0.5 to 10%. The above manufacturing method is based on the glow discharge decomposition method, but there are also sputtering methods, ion blating methods, and methods in which Si is evaporated while introducing activated or ionized hydrogen in a hydrogen discharge tube. (In particular, Japanese Patent Application Laid-Open No. 56-78413 (Patent Application No. 54-152) filed by the present applicant)
The above photoreceptor can also be manufactured by the method of No. 455). Hereinafter, the present invention will be described with reference to specific examples. By glow discharge decomposition method, the first
An electrophotographic photoreceptor having the structure shown in the figure was manufactured. That is, first, after cleaning the surface of one substrate 41 as a support, for example, a drum shape with a smooth surface, it is placed in a vacuum chamber 52 shown in FIG. 2, and the gas pressure in the vacuum chamber 52 is set to 1 6
Torr, and exhaust the air, and keep the substrate 41 at a predetermined temperature, particularly 100 to 350°C (preferably 150°C).
-300°C). Next, high-purity Ar gas was introduced as a carrier gas, high-frequency power with a frequency of 13.56 MHz was applied under a back pressure of 0.5 Torr, and preliminary discharge was performed for 10 minutes. Next, a reactive gas consisting of 5tH4 and B2H6 or P, H3 is introduced and electrolyzed at a flow rate ratio of 1:1:1, thereby forming a P-type a-3iCO:H layer 44 and a-S, which have a charge blocking function.
i CQ:H charge transport layer 42 at 6 μm/hr
The films were sequentially formed to a predetermined thickness at a deposition rate of . Continuing, B2H
The supply of 6 and CH4 was stopped, and SiH4 was decomposed by discharge to form an a-3i:H layer 43 with a thickness of 5 μm. Subsequently, the a-3iCO:H intermediate layer 46 is formed by changing the flow rate ratio to perform glow discharge decomposition and changing the film thickness.
An iCO:H surface protective layer 45 was further provided to complete the electrophotographic photoreceptor. The structure of the photoreceptor thus produced was summarized as follows. (4), Charge generation layer; a-3t:H (film thickness 5 μm) (5
), charge blocking layer (6), support Al cylinder (mirror polished finish) Next, various tests were conducted using each of the above photoreceptors as follows. ±U is U degree As shown in Figure 3, 0,
A load W is applied to the 3R diamond needle 70, and the photoreceptor is moved by the motor 71.
Rotate it with and scratch it. Next, the electrophotographic copying machine U-B
An image is produced using a modified machine ix1600 (manufactured by Konishiroku Photo Industry Co., Ltd.), and the scratch strength (g) of the photoreceptor is determined by the load at which a white streak appears on the image. ■After acclimatizing the photoconductor in a modified electrophotographic copying machine U-Bix4500 (manufactured by Konishiroku Photo Industry Co., Ltd.) for 24 hours in an environment with an image flow temperature of 33°C and a relative humidity of 80%, the developer, paper, After 1000 copies were made without contact with the blade, an image was produced, and the degree of image blurring was determined based on the following criteria. ◎There is no image blurring at all, and the reproducibility of 5.5-point alphabetic characters and thin lines is good. ○: 5.5 point alphabetic characters are slightly thicker. △: 5.5 point letters are crushed and difficult to read. X: 5.5 point English letters are illegible. By measuring the potential using a modified V U-B ix 2500,
The surface potential of the photoreceptor that remains even after being irradiated with static eliminating light 301ux-see having a peak at 400 nm. Surface potential immediately before development measured with a 360SX type electrometer (manufactured by Trek) using a modified B ix 2500 machine (manufactured by Konishiroku Photo Industries, Ltd.), a photoconductor inflow current of 200 μA, and no exposure. ” 'E' 1ux°secUsing the above device, the long wavelength component of 62'On Tr1 or more of the image exposure wavelength is sharply cut using a dichroic mirror (manufactured by Koshinko Co., Ltd.), and the surface potential is halved from 500μ to 250V. The exposure amount required to
Image quality was evaluated as follows using a modified U-Bix 2500 machine (manufactured by Konishiroku Photo Industry ■). Image quality ◎ Image density is sufficiently high, resolution and gradation are good, and the image is clear with no white streaks or white spots. In other words, the image is extremely good. ○: Good image △: Image practically acceptable ×: Image not practically acceptable The results are summarized in FIG. 4. From these results, it can be seen that if a photoreceptor is produced based on the present invention, a photoreceptor excellent in each performance for electrophotography can be obtained.

[Brief explanation of the drawing]

1 to 4 show examples of the present invention, in which FIG. 1 is a sectional view of an a-3i photoreceptor, FIG. 2 is a schematic sectional view of a glow discharge device, and FIG. 3 is a sectional view of a glow discharge device. A schematic diagram of the scratch strength tester and FIG. 4 are a table showing the characteristics of each photoreceptor. FIG. 5 is a schematic sectional view of a conventional electrophotographic copying machine. In addition, in the symbols shown in the drawings, 39...a-3i type photoreceptor 41...
...Support (substrate) 42 ...Charge transport layer 43 ...Charge generation layer 44 ...Charge blocking layer 45...
. . . Surface modified layer 46 . . . Intermediate layer.

Claims (1)

[Claims] 1. A charge transport layer made of amorphous hydrogenated and/or fluorinated silicon containing carbon atoms and/or nitrogen atoms and oxygen atoms, a charge generation layer made of amorphous hydrogenated and/or fluorinated silicon, and carbon atoms and an intermediate layer made of amorphous hydrogenated and/or fluorinated silicon containing oxygen atoms, and a surface modification made of amorphous hydrogenated and/or fluorinated silicon containing more carbon atoms and oxygen atoms than the intermediate layer, respectively. A photoreceptor consisting of layers laminated one after another.